rear derailler issues

[Veloce]

The setup: 8 speed sora

 

The Problem: Gear shifting is perfect from the second to smallest sprocket up to the largest sprocket but I cannot shift into the smallest sprocket. The shifter cable is completely loose by this stage so it seems as if the spring tension which returns the derailler to its rest position is a bit light in the pants. If I give it a helping hand by pushing the derailler towards the dropout it then engages the smallest sprocket and stays there. The limit screws are adjusted correctly as a manual operation of the derailler engages all the sprockets. Could the spring tension be a bit weak is something else causing this problem??

[Johan Bornman]

I think in spite of your view on the limit screws, your H limit screw is preventing the jockey from moving freely to the smallest sprocket. Take the chain off and see if the guide pulley lines up exactly under the smallest sprocket all by itself. In other words, chain off, cable off.

 

Edit: Whilst the chain is off, does the jockey snap back freely to its default position? A slow spring (very, very rare) will show up if you allow the jockey to snap back to base.

 

 

Johan Bornman2009-04-02 12:41:35

[Veloce]

Thanks JB, will give it a try now...

[100Tours]

Is the derailleur straight? get someone with a hanger alignment guage to check it for you.  Skew hangers are hard to see and very hard to diagnose.

 

google Park Tool DAG-1 if you want to know what it looks like.